Propel/repel dispensers have been used for some time to house and dispense solid materials such as deodorant sticks. Such devices generally include a container with a product outlet, a cover over the outlet, a piston to advance or retract the material being dispensed toward or away from the outlet, respectively, and means to effect such advancement or retraction.
Often, propel/repel dispensers are top-filled with molten deodorant material through the product outlet with the piston fully retracted from the outlet. The deodorant material is then allowed to cool and solidify as a stick shaped like the interior of the dispenser. However, during such solidification, the stick contracts, causing the top to assume a concave, uneven appearance. Further, top-filled solid stick deodorants tend to dry out due to their contact with air even before actual use. Examples of solid stick dispensers suitable for top filling include: U.S. Pat. No. 2,818,167 to McKinley; U.S. Pat. No. 2,980,246 to Leshin; U.S. Pat. No. 3,907,441 to Idec; U.S. Pat. No. 4,232,977 to Chutter; U.S. Pat. No. 4,363,560 to Gentile; U.S. Pat. No. 4,521,127 to Tomburo et al.; and U.S. Pat. No. 4,580,920 to Schmidt.
To avoid the problems encountered with top-filled dispensers, it has been proposed to place a cover with a molding surface over the product outlet of a solid stick dispenser and then fill the dispenser through the bottom. As the molten material cools and solidifies, the resulting stick assumes the smooth, attractive configuration of the interior of the container and molding surface. Bottom-filling has the added advantage of limiting the deleterious exposure of the deodorant stick to air.
One technique of bottom-filling is to fill the container through its bottom before the stick advancement mechanism is installed. After filling is completed, but before solidification of the material to be dispensed, the stick advancement mechanism is installed. Examples of such bottom-filled dispensers include: U.S. Pat. No. 4,369,158 to Woodruff et al.; U.S. Pat. No. 4,552,161 to Hill et al.; U.S. Pat. No. 4,595,124 to Duval et al.; U.S. Pat. No. 4,621,935 to Sussman; U.S. Pat. No. 4,664,547 to Rosenwinkel; U.S. Pat. No. 4,700,448 to Parker; and U.S. Pat. No. 4,702,399 to Davis.
Filling solid stick dispensers before they are completely assembled and then subsequently completing assembly is a common, but complicated and messy procedure. It has, therefore, been desired to produce a dispenser which can be bottom-filled when fully assembled, as disclosed by U.S. Pat. No. 4,298,036 to Horvath ("Horvath"), U.S. Pat. No. 4,545,696 to Carluccio ("Carluccio"), and U.S. Pat. No. 4,605,330 to Crowley et al. ("Crowley").
In the dispenser of Horvath, liquid product is poured through a screw stem and flows into the container through a rectangular opening. After the product is solidified, a bottom plug is inserted.
In Carluccio's dispenser, a product is charged into the container from its bottom through aligned fill holes. After filling is completed, a plug is snapped into place.
Crowley's dispenser is filled from the bottom through a bore, skeletal mounting means, and the skeletal structure of a follower. After filling is completed, a closure seal is installed to cover the bore.
In the dispensers of Horvath, Carluccio, and Crowley, the passages for bottom-filling cannot themselves be closed--i.e., they are always available for fluid passage. The dispenser must, therefore, be held in an inverted position until the molten deodorant material has solidified and a plug installed. Use of a plug increases manufacturing costs by requiring an additional component part and additional manufacturing steps.